Double-flow turbojet engine afterburner

FIELD: turbojet engines.

SUBSTANCE: proposed afterburner of double-flow turbojet engine contains prechamber with ring flame stabilizers arranged at outlet of diffuser formed by its housing and fairing of rear support of turbine, lobe-type mixer of flows of outer and inner loops secured on support. Periphery part of afterburner and space of outer loop communicate through at least three half-wave acoustic waveguides. Outputs of half-wave acoustic waveguides are arranged in plane of prechamber, and inputs, before mixer. Length of acoustic waveguides is determined by protected invention.

EFFECT: enlarged range of effective suppression of tangential and radial modes of fluctuations of gas pressure and velocity, simplified design, reduced mass of afterburner owing to suppression of pressure fluctuations.

3 cl, 4 dwg

 

The invention relates to aircraft engine industry, namely to design afterburner turbofan engine.

Known afterburning chamber of a gas turbine engine, comprising a housing and installed in it the front of the device with the annular flame stabilizers and anti-vibration screen, installed in the housing (1).

The disadvantage of it is the damping of pressure fluctuations in a narrow range of frequencies.

Known afterburner chamber bypass turbofan engine, which contains the set of front housing device with a ring stabilizers, flame, placed at the exit of the diffuser, formed his body and fairing turbine rear bearing support, radar mixer flows of external and internal contours, fixed on a support (2).

This afterburning chamber upon occurrence of a spontaneous mode of vibration of the combustion does not have a device to suppress the energy of the generated tangential or radial modes of oscillation pressure and gas velocity.

Also known afterburning chamber of a gas turbine engine containing a device for absorption of acoustic oscillations of the gas acting as a resonant absorber (Helmholtz resonator), made in the fairing turbine rear bearing support in the form of a perforation at the two sites, the city is x at a certain length relative to the front of the device, with bushings and plugs of porous material in them in front part (3).

This afterburner chamber at the onset of the mode of vibration of the combustion DAMPS vibration, but is heavy and complicated design.

The objective of the invention is the extension of the range of effective suppression of the tangential and radial modes of oscillation of the pressure and velocity of gas, simplifying the design and reducing the mass of afterburners.

The task is solved in that in the afterburner turbofan engine, which contains the set of front housing device with a ring stabilizers, flame, placed at the exit of the diffuser, formed his body and fairing turbine rear bearing support, and radar mixer flows of external and internal contours, mounted on the support, the peripheral part of the afterburning chamber and the cavity of the outer contour indicated by at least three half-wave acoustic waveguides, while their outputs are located in the plane of the front of the device, and inputs before the mixer, and the length of the acoustic waveguide is determined from the ratio

where λ - wavelength tangential or radial oscillation modes.

In addition, in the afterburner from the entrance to the acoustic waveguide or exit may be additional is but has a quarter-wave resonator, closed ends and communicated by the channel with the cavity of the waveguide, located in the middle, while the length of the resonator determines the ratio:where λ - wavelength tangential or radial oscillation modes, and a quarter-wave resonators in the form of cavities separated by a wall of a toroidal ring, reported channels with acoustic waveguides.

Informing the peripheral portion of the afterburner with the cavity of the outer contour, at least three half-wave acoustic waveguides, we obtain the maximum removal of acoustic energy into the outer contour of the engine vibration when burning.

Setting with half-wave acoustic waveguides advanced through a common channel of a quarter-wave resonators, we can increase the loss of wave energy inside the waveguides.

Following a quarter-wave resonators in the form of cavities separated by a wall of a toroidal ring provided with a half-wave acoustic waveguides channels located in the middle of their length, we perform a compact support structure device that works well in terms of turbojet engines with low hydraulic losses.

Calculating the length of the half-wave structures is practical waveguides and the length of a quarter-wave resonators, we can run the device for suppressing vibrations of vibratory combustion and thus to provide afterburners without regular oscillations in a wider range of operating modes. The device required for this purpose, a more simple and less weight.

It provides an objective of the invention is the extension of the range of effective suppression tangential or radial modes of oscillation of the pressure and velocity of gas, simplifying the design and reducing the mass of afterburners.

Figure 1 shows the longitudinal section of the afterburner with a half-wave acoustic waveguide.

Figure 2 shows a longitudinal section afterburners with a half-wave acoustic waveguide and an additional quarter-wave resonator.

Figure 3 shows a longitudinal section afterburners with a half-wave acoustic waveguide and a quarter-wave resonator, made in the form of cavities separated by a wall of a toroidal ring.

4 shows a section a-a figure 3 for a quarter-wave resonators and waveguides.

Afterburning chamber contains installed in the front housing 1, the device 2 with the annular flame stabilizers 3, placed at the exit of the diffuser 4, formed by the housing 1 and 5 rear fairing support 6 turbine 7. On the support 6 sacramentosan 8 external threads 9 and 10 internal circuits, peripheral part 11 afterburners and the cavity 12 of the outer contour 9 reported half-wave acoustic waveguides 13 output 14 located in the plane 15 of the front of the device 2 and 16 inputs before the mixer 8. The length of the acoustic waveguide is determined from the relation:where λ - wavelength tangential or radial oscillation modes. From the entrance 16 into the acoustic waveguide 13 and the output 14 from it additionally has a quarter-wave resonator 17, closed at the ends 18, 19 and communicated by the channel 20 with the cavity 21 of the waveguide 13, which is located in the middle. The length of the resonator 17 is determined from the relation:where λ - wavelength tangential or radial oscillation modes. A quarter-wave resonators 17 can be made in the form of cavities 22 are separated by walls 23, 24 of the toroidal ring 25 and is in communication with the acoustic waveguides 13 channels 20 arranged in the middle of their length.

When working afterburners in the vibration mode of combustion in any form transverse pressure fluctuations on the waveguide 13 in the outer contour 9 is a plane wave. Because the length of the acoustic waveguide 13 is defined close to 0.5 λin all cases, fluctuations (tangential and radial) will be the maximum removal energy of the acoustic oscillations of the cavity 12 of an external circuit 9. Thanks to the presence in the construction of an additional quarter-wave resonators 17, acoustically connected through channels 20 with the waveguides 13, loss of wave energy increase due to the damping of vibrations in them, the loss of wave energy of the transverse oscillations in the coupled system of waveguides 13 and the cavities 17 in the cavity 12 will be maximum.

Thus, selecting the length of the acoustic waveguides 13 and installed quarter-wave resonators 17, you can set the device to suppress the acoustic oscillations of the transverse modes of oscillation in the afterburner vibratory combustion.

Literature

1. Skubachevskii G.S. Aviation gas turbine engines. Design and calculation details. Moscow: Mashinostroenie, 1969. S.

2. Kopelev SZ, Gurov, S.V. Thermal condition of the structural elements of aircraft engines. Moscow: Mashinostroenie, 1978. S, 178. Is.

3. RF patent №2117806, F 02 To 3/10,15.02.1995.

1. Afterburner chamber bypass turbofan engine, which contains the set of front housing device with a ring stabilizers, flame, placed at the exit of the diffuser, formed his body and fairing turbine rear bearing support, radar mixer flows of external and internal contours, fixed on a support, characterized in that the peripheral californai chamber and the cavity of the outer contour of the reported at least three half-wave acoustic waveguides, while their outputs are located in the plane of the front of the device, and inputs before the mixer, and the length of the acoustic waveguide is determined from the ratio

where λ - wavelength tangential or radial oscillation modes.

2. Afterburner chamber according to claim 1, characterized in that the side entrance to the acoustic waveguide or withdraw from it additionally has a quarter-wave resonator, closed at the ends and communicated by the channel with the cavity of the waveguide, located in the middle, while the length of the resonator is determined from the ratio

where λ - wavelength tangential or radial oscillation modes.

3. Afterburner chamber according to claim 2, wherein the quarter-wave resonators in the form of cavities separated by a wall of a toroidal ring, reported channels with acoustic waveguides.



 

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